Typically the method of removal of debris from oil and gas wells includes scrapers or brushes, which mechanically clean the interior casing of the well. Such scrapers or brushes are typically run as part of a dedicated wellbore cleanup system, which is implemented after a well has been drilled, cased and cemented.
More recent developments have seen the introduction of casing scrapers that are run as part of the drilling string. Such scrapers generally include retracted blades, for run in, and extended blades, which are activated such that the blades make contact with the casing wall when the cleaning action is required.
Typically, known casing scrapers comprise axial slots and blades that extend from the axial slots to make contact with the casing surface.
Scrapers comprising axial slots and blades extending therefrom are typically operated by combined slow axial movement and high speed rotational motion such that the blades are reamed to ensure contact with the entire 360 degree surface of the casing wall to be effective in dislodging debris from the entire 360 degree surface of the casing wall. Using this method to clean casing is time consuming and as a result the time and cost of cleaning the entire wellbore prohibits the requirement to do so.
It is desirable to provide an improved downhole cleaning apparatus.